package main

import (
	"encoding/xml"
	"fmt"
	"io/ioutil"
	"os"
	"strings"
	"strconv"
)

type inv_accnts struct {
	id string
	taxval int
	tax bool
	buy bool
}

//
// accounts considered in tax included balance check
//
var iaa []inv_accnts = []inv_accnts{
// wareneingang 19% and 7% (note: pids!)
 { "8e3b7c42e3173ed85f3d4736e82afb4d",19,false,true },
 { "0cfd2ceb45fff89b9d1b7ce3af66cdf3", 7,false,true },
 { "e3acc2865dbf931e41cf2b90240de5c2",19,false,true },
 { "b1d04ad157cac569f4299d4ddf94ed6f",19,false,true },
 { "4394ed4ffa7266f8f8731080926a7a61",19,false,true },
 { "4196ee026d1bdb785df2c975fca91ae0",19,false,true },
// aids ...
 { "cb67d346eac01c2b66e2394df4e8d6e8",19,false,true },
// abziehbare vst 19% and 7%
 { "7c449e13125d6b93043f963628106db2",19,true,true },
 { "006643c1c0a91f2b40614c75a49c6295", 7,true,true },
// --- sales
// receipts
 { "f3e905732b729ba096a50dab60559ce7",19,false,false },
 { "66c1b04bd897766cb2be538094e1db6a", 7,false,false },
 { "1d20024badc11a99a8e1cf3a9a64a501",19,false,false },
 { "9772f4e231f6f5e3100132cc53eb3447",19,false,false },
// ust
 { "e4bd6ff52408be8076f24aeb105893d9",19,true,false },
 { "38bf40d16529f2a1e611c073c6c1dc9c", 7,true,false },
}

//
// account exceptions
//
// account exceptions: nineteen to seven
var n2s_exc = []string{
}
// account exceptions: nineteen to zero
var n2z_exc = []string{
	"4970 Nebenkosten des",
	"4910 Porto",
}
// transaction exceptions: nineteen to seven
var n2s_exc_ta = []string{
	"GEMA",
}
// transaction exceptions: nineteen to zero
var n2z_exc_ta = []string{
	"Deutsche Post",
	"gesetz IHK",
	"Gesundheitsbelehrung",
	"Gewerbezentralregister",
	"Entgeltabrechnung siehe Anlage",
	"ENTGELT SPK",
	"ttenrecht und F",
	"Unterrichtung Gastst",
	"MPLC",
}

// transacion exception list --- the rest, required?
var trn_exc = []string{
}

//
// accounts which will be summed up
//

type sum_accnt struct {
	name string
	aid string
	valplus int
	valminus int
}

var summed_accounts = []sum_accnt{
	{"Bankkonto","02ea930fdcc500cf7d3a21b80a126eb0",0,0},
	{"Kasse","04e71353130ccb554ebaf4c2438d6b2f",0,0},
}

// account maps
type amap struct {
	pid string // parent id
	num int // account number
	taxval int // 7 or 19
	buy bool // buy or sales
	tax bool // tax or non-tax(=goods) account
}

// xml
type Account struct {
	XMLName xml.Name `xml:"account"`
	Name string `xml:"name"`
	AccountId string `xml:"id"`
	ParentId string `xml:"parent"`
}
type Split struct {
	XMLName xml.Name `xml:"split"`
	Id string `xml:"id"`
	Value string `xml:"value"`
	Quantity string `xml:"quantity"`
	AccountId string `xml:"account"`
}
type Transaction struct {
	XMLName xml.Name `xml:"transaction"`
	Id string `xml:"id"`
	Date string `xml:"date-posted>date"`
	Description string `xml:"description"`
	Spl []Split `xml:"splits>split"`
}
type ParsedData struct {
	XMLName xml.Name `xml:"gnc-v2"`
	DataCnt []string `xml:"count-data"`
	Accnt []Account `xml:"book>account"`
	Trn []Transaction `xml:"book>transaction"`
}

// tax
type TaxReport struct {
	Expenses [2]int
	InputTax [2]int
	ExpExc [2]int
	ITExc [2]int
	Receipts [2]int
	SalesTax [2]int
}

// 'global' data
var data ParsedData
var tax_report TaxReport

func main() {

	// argv
	sel_date := ""
	if len(os.Args) > 1 {
		sel_date = os.Args[1]
	}

	// open xml file
	file, err := os.Open("c13_skr03.gnucash")
	if err != nil {
		fmt.Println("Error opening file:", err)
		return
	}
	defer file.Close()

	// read xml file
	xmldata, err := ioutil.ReadAll(file)
	if err != nil {
		fmt.Println("Error reading file:", err)
		return
	}

	// unmarshal xml data
	err = xml.Unmarshal(xmldata,&data)
	if err != nil {
		fmt.Println("Error unmarshaling xml data:", err)
		return
	}

	// whooha, this is our data!
	fmt.Println("Parsed accounts:",len(data.Accnt))
	fmt.Println("Parsed transactions:",len(data.Trn))
	fmt.Println("")

	accnt := make(map[string]amap)

	for ac := range data.Accnt {
		aid := data.Accnt[ac].AccountId
		pid := data.Accnt[ac].ParentId
		for iac := range iaa {
			// consider account if pid or aid matches
			if pid == iaa[iac].id || aid == iaa[iac].id {
				taxval := iaa[iac].taxval
				for ec := range n2s_exc {
					if strings.Contains(data.Accnt[ac].Name,
					                    n2s_exc[ec]) {
						taxval=7
						break
					}
				}
				for ec := range n2z_exc {
					if strings.Contains(data.Accnt[ac].Name,
					                    n2z_exc[ec]) {
						taxval=0
						break
					}
				}
				accnt[aid]=amap{
					pid,
					ac,
					taxval,
					iaa[iac].buy,
					iaa[iac].tax,
				}
				break
			}
		}
	}

	// check transactions ...
	for tc := range data.Trn {
		// check balance ...
		check_balance(&data.Trn[tc],accnt,sel_date)
	}

	// tax report
	fmt.Println("Umsatzsteuervoranmeldung (19% | 7%):")
	fmt.Println("------------------------------------")
	fmt.Println("Aufwendungen:",tax_report.Expenses[0],
	                            tax_report.Expenses[1]);
	fmt.Println("ohne Ausn.  :",tax_report.Expenses[0]-
	                            tax_report.ExpExc[0],
	                            tax_report.Expenses[1]-
	                            tax_report.ExpExc[1]);
	fmt.Println("gesch. Vst. :",int((tax_report.Expenses[0]*19)/100.0),
	                            int((tax_report.Expenses[1]*7)/100.0))
	fmt.Println("ohne Ausn.  :",int(((tax_report.Expenses[0]-
	                                 tax_report.ExpExc[0])*19)/100.0),
	                            int(((tax_report.Expenses[1]-
	                                 tax_report.ExpExc[1])*7)/100.0))
	fmt.Println("Vorsteuer   :",tax_report.InputTax[0],
	                            tax_report.InputTax[1],
	            "->",tax_report.InputTax[0]+tax_report.InputTax[1]);
	fmt.Println("------------------------------------")
	fmt.Println("Einnahmen   :",-tax_report.Receipts[0],
	                            -tax_report.Receipts[1]);
	fmt.Println("gesch. Ust. :",int((-tax_report.Receipts[0]*19)/100.0),
	                            int((-tax_report.Receipts[1]*7)/100.0));
	fmt.Println("Umsatzsteuer:",-tax_report.SalesTax[0],
	                            -tax_report.SalesTax[1]);
	fmt.Println("------------------------------------")

	// summed accounts
	fmt.Println("")
	fmt.Println("Summen einiger Konten:")
	fmt.Println("----------------------")
	for sac := range summed_accounts {
		saccnt := summed_accounts[sac]
		fmt.Println(" Konto: ",saccnt.name)
		fmt.Println("     +: ",saccnt.valplus)
		fmt.Println("     -: ",saccnt.valminus)
	}
}

func check_balance(ta *Transaction,accnt map[string]amap,sel_date string) bool {

	// check date
	tdate := strings.Fields(ta.Date)[0]
	if !strings.Contains(tdate,sel_date) {
		return true
	}

	// exceptions
	tv_ow := -1
	for ec := range n2s_exc_ta {
		if strings.Contains(ta.Description,n2s_exc_ta[ec]) {
			tv_ow=7
			break
		}
	}
	for ec := range n2z_exc_ta {
		if strings.Contains(ta.Description,n2z_exc_ta[ec]) {
			tv_ow=0
			break
		}
	}

	// [taxval: 19=0 7=1][tax: no=0 yes=1][buy: no=0 yes=1]
	var sum [2][2][2]int

	// loop over splits within the transaction
	for sc := range ta.Spl {
		aid := ta.Spl[sc].AccountId
		//accnt[aid].tax
		// loop over all considered accounts (defined earlier as global)
		for iac := range iaa {
			tv := int(0)
			// taxval changed by exception
			if tv_ow != -1 {
				if tv_ow == 7 {
					tv=1
				}
				if tv_ow == 0 {
					// reset taxvalues of involved accounts
					// (to drop an error)
					if accnt[aid].tax {
						if accnt[aid].taxval==7 {
							tv=1
						}
					} else {
						continue
					}
				}
			// taxval as defined by account
			} else {
				if accnt[aid].taxval == 0 {
					if accnt[aid].tax {
						fmt.Println("FATAL!");
					}
					continue
				}
				if accnt[aid].taxval == 7 {
					tv = 1
				}
			}
			// tax
			tax := int(0)
			if iaa[iac].tax {
				tax = 1
			}
			// buy
			buy := int(0)
			if iaa[iac].buy {
				buy = 1
			}
			// match! add to sum and break.
			match := bool(false)
			// check pids if ...
			if tax == 0 && buy == 1 {
				_, exists := accnt[aid]
				if exists {
					// pids
					if accnt[aid].pid == iaa[iac].id {
						match = true
					}
				}
			}
			// ... however, always check aids
			if aid == iaa[iac].id {
				match = true
			}
			if match {
				inc, _ := strconv.Atoi(strings.TrimSuffix(ta.Spl[sc].Value,"/100"))
				sum[tv][tax][buy] += inc
				break
			}
		}
		// now get the sums
		for sac := range summed_accounts {
			if summed_accounts[sac].aid == aid {
				inc, _ := strconv.Atoi(strings.TrimSuffix(ta.Spl[sc].Value,"/100"))
				if inc >= 0 {
					summed_accounts[sac].valplus += inc
				} else {
					summed_accounts[sac].valminus += inc
				}
			}
		}
	}

	// check for exceptions
	exc := false
	for ec := range trn_exc {
		if strings.Contains(ta.Description,trn_exc[ec]) {
			exc = true
			break
		}
	}
	//for ac := range accountlist {
	//	if strings.Contains(data.Accnt[anum].Name,accountlist[ac]){
	//		return true
	//	}
	//}

	// tax report
	for tv := 0; tv<2; tv++ {
		tax_report.Expenses[tv] += sum[tv][0][1]
		tax_report.InputTax[tv] += sum[tv][1][1]
		tax_report.Receipts[tv] += sum[tv][0][0]
		tax_report.SalesTax[tv] += sum[tv][1][0]
		if exc {
			tax_report.ExpExc[tv] += sum[tv][0][1]
			tax_report.ITExc[tv] += sum[tv][1][1]
		}
	}

	// check
	var expected [2]int
	check := true
	for buy := 0; buy < 2; buy++ {
		expected[0]=int((sum[0][0][buy]*19)/100.0)
		expected[1]=int((sum[1][0][buy]*7)/100.0)
		for tv :=0; tv < 2; tv++ {
			if expected[tv] < sum[tv][1][buy]-1 ||
			   expected[tv] > sum[tv][1][buy]+1 {
				var sb, st string
				if buy == 0 {
					sb = "Umsatzsteuer"
				} else {
					sb = "Vorsteuer"
				}
				if tv == 0 {
					st = "19%"
				} else {
					st = " 7%"
				}
				check = false
				fmt.Printf("%s %s: ",sb,st);
				fmt.Printf("Erwarte %d statt %d aus %d! ",
				           expected[tv],
				           sum[tv][1][buy],sum[tv][0][buy]);
				if(!exc) {
					fmt.Printf("\n");
				} else {
					fmt.Printf("Ausnahme greift!\n");
					fmt.Printf("(%s)\n\n",ta.Description)
				}
			}
		}
	}
	if !check && !exc {
		fmt.Println("am",ta.Date)
		fmt.Printf("(%s)\n",ta.Description)
		fmt.Println("Beteiligte Konten:")
		for ic := range ta.Spl {
			found := strings.TrimSuffix(ta.Spl[ic].Value,"/100")
			aid := ta.Spl[ic].AccountId
			_, exists := accnt[aid]
			if exists {
				num := accnt[aid].num
				fmt.Printf("  %s => %s\n",data.Accnt[num].Name,
				                          found)
			} else {
				fmt.Printf("  %s => %s\n",aid,found)
			}
		}
		fmt.Println("")
	}

	return check
}

func round(v float64) int {
	if v < 0.0 {
		v -= 0.5
	} else {
		v += 0.5
	}
	return int(v)
}